Taran drawing Drynwyn in the final book, and slaying the Nigh Invulnerable Cauldron-Born in a single blow.
Also, when Taran fights Dorath, he uses a sword he forged himself, while Dorath fights with the sword he stole from Taran (which was given to Taran at the beginning of The Black Cauldron). Taran's new blade proves so much better that it actually shatters the old one.
Dallben gets one when Pryderi comes with a group of soldiers to kill him.
Rhun, previously identified as a well-meaning clod, pulls off a beautiful one in The High King when he confuses the enemy into thinking he's brought a giant army with him.